Imaging in Pediatric Abdominal Emergencies
William A. Mize M.D.
University of Minnesota Hospital and Clinic
Pediatric Abdominal Emergencies
- Necrotizing enterocolitis
- Malrotation with midgut volvulus
- Hypertrophic pyloric stenosis
- Intussusception
- Appendicitis
Necrotizing Enterocolitis
Neonatal bowel disorder related to hypoxic stress
80% in premature infants
Term infants usually have other diseases
Onset 3-6 days of age
Necrotizing Enterocolitis - Evaluation
- Plain films of abdomen
- Do horizontal beam film if other findings present - free air view
- Contrast studies:
- Not indicated in acute phase
- Used on followup for strictures
Necrotizing Enterocolitis - Plain Film Findings
- Focal bowel dilatation
- Pneumatosis intestinalis
- Portal gas
- Pneumoperitoneum - the only imaging indication for surgical exploration
Malrotation
- Nonrotation - usually asymptomatic
- Incomplete rotation - present with early obstruction
- Midgut volvulus
- Ladd bands
Malrotation - Evaluation
- Best test to assess rotation is upper GI
- Duodenal-jejunal junction (DJJ) position is key finding
- Position of cecum less reliable
Bowel Rotation on Upper GI
- Best to spot first pass through duodenal sweep
- Normal
- DJJ to left of midline at same level as pylorus/duodenal bulb
- Rest of small bowel can be anywhere, including RUQ
Bowel Rotation on Upper GI
- Variants
- Redundancy of proximal duodenum
- DJJ displaced downward by gastric/bowel distention
- Inverted sweep
- DJJ ''slightly'' low
Bowel Rotation on Upper GI - Problem Cases
- May be useful to follow contrast to cecum
- DJJ-cecum distance provides good estimate of length of mesenteric root, risk for volvulus
Malrotation with Midgut Volvulus
- Sudden onset of bilious vomiting in a neonate is a radiologic/surgical emergency
Malrotation with Midgut Volvulus - Plain Films
- Often normal
- Gastric outlet obstruction pattern
- Duodenal obstruction pattern
- Apparent distal small bowel obstruction - closed loop obstruction (ominous)
Malrotation with Midgut Volvulus - Upper GI
- Duodenal-jejunal junction low and to the right
- Proximal duodenal dilatation with tapering to ''beak''
- Spiral pattern
- ''Z'' pattern with Ladd bands
Hypertrophic Pyloric Stenosis (HPS)
- Hypertrophy of the circular muscle of the pylorus
- 2nd to 6th week, peak 3 weeks
- M:F 4:1
- Nonbilious, projectile vomiting
- Hyperperistalsis
- Palpable ''olive''
HPS - Plain Film Findings
- Gastric distention - variable
- Visible peristaltic waves
HPS - Evaluation
- Very good story - sonography
- Mediocre story - upper GI
- Combined ''HPS evaluation''
- Ultrasound first
- If obviously positive, stop
- If not, follow with upper GI
- Flat fee
HPS - Sonography
- Muscle thickness > 3mm
- Channel length > 15mm
- Diameter > 8mm
- Usually obvious when positive
HPS - Upper GI Technique
- Do through NG tube
- Empty gastric contents through tube
- Start in right lateral position
- Use small volume of contrast, large volume of air
HPS - Upper GI Findings
- Elongated, nondistensible pyloric canal
- Shoulder sign
- Double/triple track
- Mushroom sign
Intussusception
- Invagination of one segment of bowel into another
- Usually ileocolic or ileoileocolic
- Peak incidence 5-9 months
- Seasonal - spring and winter
- Possible association with viral illness/Peyer patch hypertrophy
Intussusception
- Slight male predominance
- Colicky abdominal pain, vomiting, bloody stools
- Palpable mass 70-80%
- Pathologic lead point more common after age 2
Intussusception - Plain Film
- May be normal
- Soft tissue mass, often in RUQ
- Small bowel obstruction
- May see intussusceptum
Intussusception - Ultrasound
- Primary diagnostic tool in some centers
- Can be used to monitor reduction using saline
- Findings:
Intussusception - Contrast Enema
- Diagnosis and treatment
- Media:
- Air
- Barium
- Water soluble contrast
Enema Reduction
- Personal comfort level is probably the best contrast selection criterion
- All have similar rates of reduction (75-85%) and perforation (1-2%)
Intussusception - Gas Vs. Liquid
- Faster
- Less mess
- More pressure control
- Higher success (?)
- Fewer perforations (?)
- Smaller perforations
Enema Reduction
- Surgical consult and IV first
- Peritonitis and/or perforation only absolute contraindications
- Crying/Valsalva helpful and protective - no sedation
Enema Reduction
- End point - free reflux into small bowel and reduction of mass
- Often see edema of ileocecal valve
- Main goal is to prevent unnecessary open reduction, select patients who need resection
Appendicitis
- Most frequent indication for pediatric abdominal surgery
- Rare in infancy
- Progressively more common with age
- Diagnosis primarily clinical
- Imaging in problem cases
Appendicitis - Plain Film
- Appendicolith - unusual but specific
- Indirect signs of RLQ inflammation
- RLQ mass effect
- Small bowel obstruction - perforation
- Free air - rare
Appendicitis - Ultrasound
- Appendix > 6mm, noncompressible, tender
- Fluid collection
- Increased flow on doppler
- Exclude other pathology
Appendicitis - CT
- Evaluation of complications
- May be useful in primary diagnosis, particularly in older children
- Inflammatory changes in peri-appendiceal fat
Summary
- Necrotizing enterocolitis
- Monitor with plain film findings
- Pneumoperitoneum = exploration
- Malrotation/midgut volvulus
- Upper GI is most direct imaging test
- True emergency
Summary HPS
- Hypertrophic pyloric stenosis
- Good story - ultrasound
- Mediocre story - upper GI
Intussusception
- Contrast enema of your choice for diagnosis/treatment
Summary Appendicitis
- Appendicitis
- Clinical problem cases are often imaging problem cases
- Plain films first
- Jury still out on ultrasound, CT
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